Various PCB (Printed Circuit Board) structures are used to allow the use of multifunctional LEDs (light emitting diodes) in automotive industry applications. While in traditional systems, materials with low-conductivity are used as PCB technology.
In another example application, FR4-based printed circuit technology is used. Potential disadvantages of this type of units are centered on the formation of local hotspots up to temperatures 20-30° C. above the maximum permissible temperatures. LEDs have a rapidly increasing performance in terms of light output. The efficiency of LEDs when used for lighting purposes in automotive industry is a proven fact. However, heat produced by diodes necessitates the use of heat shields or certain additional components for heat dissipation, resulting in a rise in the cost of lamps, in addition to some certain disadvantages arising out of very high heat flow produced by low-power chips in a very small space. When LED resources are intensively used, e.g. in headlight applications, light output increases, but the resulting heat becomes a significant problem. What's more, batch intensity of LEDs further leads to a physical problem both in itself and outside. In the state of the art, there are some patents dealing with double-sided support boards of LED lighting units. In those patents, it is noted that the areas of back plate localizing the support board are in interaction with certain indents created on the second side of the support board. In general applications, these boards are plastic-based (FR4) materials. Manufacturers are unaware of local hotspots, because LED technology is not widely used yet. Standard printed boards are FR4 boards with very low conductivity and affordable prices, as well as ceramic and direct-bonded copper constructions with better conductivity but higher prices and less durability. Large cooling components and extra materials are required to cool down the traditionally and habitually used FR4 board. For example, thermal by-products, thermal paths and screws are used therein. This kind of design further requires a high level of hand-workmanship for assembly works.
In the case of multifunctional use of LEDs, LEDs are combined with cutting edge PCB technology. In the relevant application, a series of LEDs are assembled on the first side of the support board. LEDs stand upright on the support board, and an electrical circuit is formed on the support board to supply power to LEDs. Said PCBs can be made of fiberglass, plastic, composite epoxy or other laminated materials. Some solutions for cooling are employed in PCB applications. Examples of cooling apparatuses include:
Such an apparatus is described in the patent application no. KR20120136527 titled “Heat-pipe integrated one body type PCB using thin film vapor deposition method for LED light”. In the said patent application, a PCB structure linked to a hollow metal body is described. Accordingly, the hollow metal body carries respectively an insulating film layer, a thin vapor deposition film layer, a copper layer and an insulating layer. A similar study is described also in the patent application no. KR20140099603. In the patent application no. KR20080062093 titled “Low voltage back light unit that is made mixing chip LED a attach PCB composition of special protection against heat structure and special processing acryl plate glass composition”, cooling holes and heat sinks opened on PCB having LED chips on both sides are described.
Another apparatus is defined in the patent application no. KR100953857 titled “A PCB unified with soft silicon pad for high speed heat dissipation of LED and the method thereof”. In the said patent application, a PCB with LED illuminators on one side and heat sinks on the other side are described. For applications with similar heat sinks, the patent applications no. KR100990331, CN102182992, CN202125895, KR101329703 can be shown as examples.
Another apparatus is described in the patent application no. KR101049887 titled “Metal PCB structure for radiant heat improvement and circuit protection of LED lighting device”. In the said patent application, epoxy-heat band layers used for heat dissipation within PCB cross-section are described.
These examples have a common basic property, characterized in that they are related to apparatuses having only LED structures on PCB and having heat sinks or similar cooling apparatuses on the other side. Cooling designs, developed for limited spaces, providing specific solutions with regard to automotive applications are needed.
In order to eliminate the disadvantages specified above, solutions are developed for PCBs used in LED lighting apparatuses in automotive industry, and having an electronic circuit on one side and LED lighting components on the other side.